The overall mourning period begins at sunset on the eve of Shiva Assar B’Tammuz, which is to say that if Shiva Assar B’Tammuz is on a Tuesday, the Three Weeks begins at sunset on Monday night. In most years, the mourning ends at midday (chatzos) on the day after Tisha B’av, which would be Wednesday afternoon in the previous example. But in years, such as this year, when the 9th of Av occurs on Shabbos, all forms of mourning basically end on the (Sunday) night after the fast of Tisha B’av.
For our purposes, we will divide the restrictions of the Three Weeks into four groups based on timing: Shiva Assar B’Tammuz until the end of Tammuz, Rosh Chodesh Av until Tisha B’av, the day of Tisha B’av, and post Tisha B’av. During the first period of time – Shiva Assar B’Tammuz until the end of Tammuz – no live or recorded music – including a cappella, see http://kshr.us/Sappirim24 - may be played in certified establishments.
The second period of time is known colloquially as “The Nine Days”. During that period, not only is music not allowed but in addition, no meat, poultry, wine, or grape juice may be served to customers at a restaurant, but they may be sold for take-out customers who will eat the food out of the certified establishment. Similarly, supermarkets may sell raw meat and poultry. As a matter of policy, certified food-trucks may not sell meat, poultry, etc. during The Nine Days. [Of course, we do not condone eating meat, poultry etc. even at home during The Nine Days, but there are enough people who have special reasons why they are permitted to eat these foods that we do not question those who choose to buy the foods and eat them at home.]
The above restrictions do not apply to wine vinegar, or on Shabbos. Furthermore, there are many leniencies in the application of these halachos for those in a hospital, nursing home, or assisted living facility, and those overseeing such establishments should consult with Rabbi Eisenbach and Rabbi Katz for direction on what may be served.
On the day before Tisha B’av, all certified food establishments must close for business at 5:00 PM. They may reopen at midday (chatzos) of Tisha B’av for carry-out service only. On the day after Tisha B’av, they must wait until midday to play music, or to serve meat, poultry, wine, or grape juice to in-house patrons. In a year such as this, where the 9th of Av is on Shabbos, they remain open all day on the Friday preceding Tisha B’av, and may open for business-as-usual on the Monday after Tisha B’av. [Meat, poultry, etc. remain forbidden on Sunday night, and should therefore not be served to in-house patrons until the morning.]